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Class 12th Atoms

The following graph represents the $T - V$ curves of an ideal gas (where $T$ is the temperature and $V$ the volume) at three pressures $P_{1}, P_{2}$ and $P_{3}$ compared with those of Charles's law represented as dotted lines.

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alok kumar singh

Contributor-Level 10

At same temperature, curve with higher volume corresponds to lower pressure.

$V_{3} > V_{2} > V_{1}$

$\Rightarrow P_{1} > P_{2} > P_{3}$

(We draw a straight line parallel to volume axis to get this)

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Class 12th Physics

If the mass of the bob in a simple pendulum is increased to thrice its original mass and its length is made half its original length, then the new time period of oscillation is $\frac{x}{2}$ times its original time period. Then the value of $x$ is:

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alok kumar singh

Contributor-Level 10

$T^{'} = 2 π \sqrt[]{\frac{?^{'}}{g}}$ where $t^{'} = \frac{l}{2}$

$T = 2 π \sqrt[]{\frac{t}{g}}$

$T^{'} = \frac{x}{2} T$

$2 π \sqrt[]{\frac{t}{2 g}} = \frac{x}{2} 2 π \sqrt[]{\frac{t}{g}}$

$\frac{1}{\sqrt[]{2}} = \frac{x}{2} \Rightarrow x = \sqrt[]{2}$

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Class 12th Chemistry

The highest number of helium atoms is in

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Payal Gupta

Contributor-Level 10

(1) 4 mol of $= 4_{A}$ atoms

(2) 4 u of $= \frac{4 u}{4 u} = 1$ atom

(3) 4 g of Helium $= \frac{4}{4}$ mole $= 1$ mole $= N_{A}$ He atom

(4) $2.2710982$ of He at STP $= \frac{2.271}{22.710982}$ mole

$= 0.1$

$= 0.1_{A}$

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Class 12th Physics

A tightly wound 100 turns coil of radius 10 cm carries a current of 7 A . The magnitude of the magnetic field at the centre of the coil is (Take permeability of free space as $4 π * 1 0^{- 7} SI$ units):

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alok kumar singh

Contributor-Level 10

The magnitude of magnetic field due to circular coil of $N$ turns is given by

$B_{C} = \frac{μ_{0} i N}{2 R}$

$= \frac{4 π * 1 0^{- 7} * 7 * 100}{2 * 0.1}$

$= 4.4 * 1 0^{- 3} T$

$= 4.4 mT$

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10 months ago

Class 12th Physics

A thin spherical shell is charged by some source. The potential difference between the two points $C$ and $P$ (in V) shown in the figure is:

(Take $\frac{1}{4 π ε_{0}} = 9 * 1 0^{9}$ SI units)

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alok kumar singh

Contributor-Level 10

For uniformly charged spherical shell,

$V = \frac{k q}{R} (For r \leq R)$

$∴ V_{C} = V_{P}$

$V_{C} - V_{P} = Zero$

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10 months ago

Class 12th Dual Nature of Radiation and Matter

The maximum elongation of a steel wire of 1 m length if the elastic limit of steel and its Young's modulus, respectively, are $8 * 1 0^{8} N m^{- 2}$ and $2 * 1 0^{11} N m^{- 2}$ , is:

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alok kumar singh

Contributor-Level 10

In the case for maximum elongation,

Stress = Elastic limit

$δ_{m a x} = \frac{σ_{elastic} * L}{Young's modulus} = \frac{8 * 1 0^{8} * 1}{2 * 1 0^{11}} = 4 * 1 0^{- 3}$

$= 4 mm$

i.e. maximum elongation is 4 mm

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10 months ago

Class 12th Physics

In an ideal transformer, the turns ratio is $\frac{N_{P}}{N_{S}} = \frac{1}{2}$ . The ratio $V_{S} : V_{P}$ is equal to (the symbols carry their usual meaning) :

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alok kumar singh

Contributor-Level 10

According to transformer ratio,

$\frac{V_{S}}{V_{P}} = \frac{N_{S}}{N_{P}} = 2 : 1$

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10 months ago

Class 12th Physics Wave Optics

A thin flat circular disc of radius 4.5 cm is placed gently over the surface of water. If surface tension of water is $0.07 N m^{- 1}$ , then the excess force required to take it away from the surface is

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alok kumar singh

Contributor-Level 10

Excess force $= T * 2 π R$

$= \frac{7}{100} * 2 * 3.14 * \frac{4.5}{100}$

$= 197.82 * 1 0^{- 4}$

$= 19.8 * 1 0^{- 3} N$

$= 19.8 mN$

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10 months ago

Class 12th English

Direction for question 13 to 16: Go through the chart given below and solve the questions based on it.

Given below are the win loss histories of four tennis players in their career.

Result/Players	P	Q	R	S
Won	23	18	10	16
Won	13	16	13	14
Lost	8	13	16	13
Lost	6	8	20	17

Who has lost the maximum percentage of matches played?

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Vishal Baghel

Contributor-Level 10

(c)

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10 months ago

Class 12th English

Direction for question 13 to 16: Go through the chart given below and solve the questions based on it.

Given below are the win loss histories of four tennis players in their career.

Result/Players	P	Q	R	S
Won	23	18	10	16
Won	13	16	13	14
Lost	8	13	16	13
Lost	6	8	20	17

As in the case above what is the highest average prize money won per money won per match by any player?

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Vishal Baghel

Contributor-Level 10

the highest average is Rs. 136

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